English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present a detailed analysis of the spatially and spectrally resolved 12COJ=2-1 and J=3-2 emission lines from the TW Hya circumstellar disk, based onscience verification data from the Atacama Large Millimeter/Submillimeter Array(ALMA). These lines exhibit substantial emission in their high-velocity wings(with projected velocities out to 2.1 km/s, corresponding to intrinsic orbitalvelocities >20 km/s) that trace molecular gas as close as 2 AU from the centralstar. However, we are not able to reproduce the intensity of these wings andthe general spatio-kinematic pattern of the lines with simple models for thedisk structure and kinematics. Using three-dimensional non-local thermodynamicequilibrium molecular excitation and radiative transfer calculations, weconstruct some alternative models that successfully account for these featuresby modifying either (1) the temperature structure of the inner disk (inside thedust-depleted disk cavity; r < 4 AU); (2) the intrinsic (Keplerian) diskvelocity field; or (3) the distribution of disk inclination angles (a warp).The latter approach is particularly compelling because a representative warpeddisk model qualitatively reproduces the observed azimuthal modulation ofoptical light scattered off the disk surface. In any model scenario, the ALMAdata clearly require a substantial molecular gas reservoir located inside theregion where dust optical depths are known to be substantially diminished inthe TW Hya disk, in agreement with previous studies based on infraredspectroscopy. The results from these updated model prescriptions are discussedin terms of their potential physical origins, which might include dynamicalperturbations from a low-mass companion with an orbital separation of a few AU.

Kinematics of the CO Gas in the Inner Regions of the TW Hya Disk